You can implement a progressive tax using UBI and a flat tax instead and thus get rid of all the loopholes and tax screwery. IMO this is what all countries should do. Corruption loves complexity.
I dream of the day that a land value tax, and only a land value tax, covers all government services. In fact, one could argue that the size of government that a land value tax supports is the maximum size.
All excellent ideas. Unfortunately I think a Federal LVT would require a Constitutional amendment, but nothing stopping us from doing this at the State level.